Logg errors at the Google Scholar fetcher and hide them from the UI

src/main/java/org/jabref/logic/importer/fetcher/GoogleScholar.java

@@ -220,7 +220,8 @@ public Page<BibEntry> performSearchPaged(ComplexSearchQuery complexSearchQuery,
                     throw new FetcherException("Fetching from Google Scholar failed.",
                             Localization.lang("This might be caused by reaching the traffic limitation of Google Scholar (see 'Help' for details)."), e);
                 } else {
-                    throw new FetcherException("Error while fetching from " + getName(), e);
+                    // throw new FetcherException("Error while fetching from " + getName(), e);
+                    LOGGER.warn("Error while fetching from " + getName(), e);
                 }
             }
             return new Page<>(complexQueryString, pageNumber, foundEntries);

src/main/java/org/jabref/logic/importer/fileformat/ACMPortalParser.java

@@ -0,0 +1,4 @@
+package org.jabref.logic.importer.fileformat;
+
+public class ACMPortalParser {
+}